Method and apparatus for processing transmit power control (TPC) commands in a wideband CDMA (WCDMA) network based on a sign metric

ABSTRACT

Method and apparatus for processing transmit power control (TPC) commands in a wideband CDMA (WCDMA) network based on a sign metric are disclosed and may include calculating a sign metric of a downlink dedicated physical channel (DPCH) based on a plurality of TPC bits received via the downlink DPCH. A value of at least one of the plurality of TPC bits may not be known when the at least one of the plurality of TPC bits is received. The sign metric may specify an error associated with the plurality of TPC bits. Transmit power may be adjusted for a signal transmitted via at least one uplink communication channel based on the calculated sign metric. At least one reliability weight value may be calculated for at least a portion of the received TCP bits, based on the calculated sign metric.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This application is a continuation of U.S. application Ser. No.11/355,111 filed Feb. 15, 2006, which in turn makes reference to:

-   U.S. application Ser. No. 11/355,110, filed Feb. 15, 2006;-   U.S. application Ser. No. 11/355,222, filed Feb. 15, 2006; and-   U.S. application Ser. No. 11/355,109, filed Feb. 15, 2006.

Each of the above state applications is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to wireless communication.More specifically, certain embodiments of the invention relate to amethod and apparatus for processing transmit power control (TPC)commands in a wideband CDMA (WCDMA) network based on a sign metric.

BACKGROUND OF THE INVENTION

Mobile communications has changed the way people communicate and mobilephones have been transformed from a luxury item to an essential part ofevery day life. The use of mobile phones is today dictated by socialsituations, rather than hampered by location or technology. While voiceconnections fulfill the basic need to communicate, and mobile voiceconnections continue to filter even further into the fabric of every daylife, the mobile Internet is the next step in the mobile communicationrevolution. The mobile Internet is poised to become a common source ofeveryday information, and easy, versatile mobile access to this datawill be taken for granted.

Third generation (3G) cellular networks have been specifically designedto fulfill these future demands of the mobile Internet. As theseservices grow in popularity and usage, factors such as cost efficientoptimization of network capacity and quality of service (QoS) willbecome even more essential to cellular operators than it is today. Thesefactors may be achieved with careful network planning and operation,improvements in transmission methods, and advances in receivertechniques. To this end, carriers need technologies that will allow themto increase downlink throughput and, in turn, offer advanced QoScapabilities and speeds that rival those delivered by cable modem and/orDSL service providers. In this regard, networks based on wideband CDMA(WCDMA) technology may make the delivery of data to end users a morefeasible option for today's wireless carriers.

In the case of a WCDMA downlink, multiple access interference (MAI) mayresult from inter-cell and intracell interference. The signals fromneighboring base stations compose intercell interference, which ischaracterized by scrambling codes, channels and angles of arrivalsdifferent from the desired base station signal. Spatial equalization maybe utilized to suppress inter-cell interference. In a synchronousdownlink application, employing orthogonal spreading codes, intra-cellinterference may be caused by multipath propagation. Due to the non-zerocross-correlation between spreading sequences with arbitrary timeshifts, there is interference between propagation paths afterdespreading, causing MAI. The level of intra-cell interference dependsstrongly on the channel response. In nearly flat fading channels, thephysical channels remain almost completely orthogonal and intra-cellinterference does not have any significant impact on the receiverperformance. Frequency selectivity is common for the channels in WCDMAnetworks.

Mobile networks allow users to access services while on the move,thereby giving end users freedom in terms of mobility. However, thisfreedom does bring uncertainties to mobile systems. The mobility of theend users causes dynamic variations both in the link quality and theinterference level, sometimes requiring that a particular user changeits serving base station. This process is known as handover (HO).Handover is the essential component for dealing with the mobility of endusers. It guarantees the continuity of the wireless services when themobile user moves across cellular boundaries.

WCDMA networks may enable a mobile handset to communicate with amultiple number of cell sites. This may take place, for example, duringa soft-handoff from one cell site to another. Soft-handoffs may involvecell sites that use the same frequency bandwidth. There may also behandoffs from one cell site to another where the two cell sites usedifferent frequencies. In these cases, the mobile handset may need totune to the frequency of the new cell site. Additional circuitry may berequired to handle communication over a second frequency of the secondcell site while still using the first frequency for communicating withthe first cell site. The additional circuitry may be an undesirableextra cost for the mobile handset. In addition, the mobile handset mayrequire different transmit power to establish and maintain acommunication link with the new cell site.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

A method and/or apparatus for processing transmit power control (TPC)commands in a wideband CDMA (WCDMA) network based on a sign metric,substantially as shown in and/or described in connection with at leastone of the figures, as set forth more completely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is an exemplary diagram illustrating a WCDMA handsetcommunicating with two WCDMA base stations, in accordance with anembodiment of the invention.

FIG. 1B is a block diagram of an exemplary radio frame format of adownlink dedicated physical channel (DPCH), in accordance with anembodiment of the invention.

FIG. 1C is a graph illustrating the effect of a sign metric as anindicator of the quality of reception of the downlink DPCH, inaccordance with an embodiment of the invention.

FIG. 2 is a block diagram illustrating a mechanism for determiningreliability weights in a WCDMA network, in accordance with an embodimentof the invention.

FIG. 3 is a block diagram illustrating another mechanism for determiningreliability weights in a WCDMA network, in accordance with an embodimentof the invention.

FIG. 4 is a block diagram of an exemplary system for weightedcombination of multiple TPC commands, in accordance with an embodimentof the invention.

FIG. 5 is a flowchart illustrating exemplary steps for determining atotal TPC command in a WCDMA network, in accordance with an embodimentof the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention provide a method and a system forprocessing transmit power control (TPC) commands in a wideband CDMA(WCDMA) network based on a sign metric. Various aspects of the methodmay comprise calculating a sign metric of a downlink dedicated physicalchannel (DPCH) based on a plurality of TPC bits received via thedownlink DPCH. A value of at least one of the plurality of TPC bits maynot be known when the at least one of the plurality of TPC bits isreceived. The sign metric may specify an error associated with theplurality of TPC bits. Transmit power may be adjusted for a signaltransmitted via at least one uplink communication channel based on thecalculated sign metric. At least one reliability weight value may becalculated for at least a portion of the received TCP bits, based on thecalculated sign metric. A total TPC command may be calculated for theuplink communication path based on the plurality of received TPC bitsand the calculated reliability weight value. A selected reliabilityweight value may be discarded from the calculation of the total TPCcommand, if the selected reliability weight value is higher than athreshold value. The transmit power may be adjusted for the uplinkcommunication channel based on the calculated total TPC command.

Uplink power control (PC) is of paramount importance for CDMA-basedsystems because the capacity of such a system is a function of theinterference level. The power transmitted by all active user equipments(UE) within a network may be controlled to limit interference levels andalleviate well-known problems such as the “near-far” effect. If there ismore than one user active, the transmitted power of non-reference usersis suppressed by a factor dependent on the partial cross-correlationbetween the code of the reference user and the code of the non-referenceuser. However, when a non-reference user is closer to the receiver thanthe reference user, it is possible that the interference caused by thisnon-reference user has more power than the reference user also referredto as the “near-far” effect.

There are two types of power-control techniques. Open-loop power-controlwhere each user equipment measures its received signal power and adjustsits transmit power accordingly and closed-loop power-control where anactive radio link (RL) measures the received signal power from all userequipments and simultaneously commands the individual user equipments toraise or lower their transmit uplink power such that the receivedsignal-to-noise ratio (SNR) from all user equipments at the radio linksis the same.

FIG. 1A is an exemplary diagram illustrating a WCDMA handsetcommunicating with two WCDMA base stations, in accordance with anembodiment of the invention. Referring to FIG. 1A, there is shown amobile handset or user equipment 120, a plurality of base stations BS122 and BS 124 and a plurality of radio links (RL), RL₁ and RL₂ couplingthe user equipment 120 with the base stations BS 122 and BS 124respectively. The user equipment 120 may comprise a processor 142, amemory 144, and a radio 146.

The processor 142 may communicate and/or control a plurality of bitsto/from the base stations BS 122 and BS 124. The memory 144 may comprisesuitable logic, circuitry, and/or code that may store data and/orcontrol information. The radio 146 may comprise transmit circuitryand/or receive circuitry that may be enabled to calculate a sign metricof a downlink dedicated physical channel (DPCH) based on a plurality oftransmit power control (TPC) bits received via the downlink dedicatedphysical channel (DPCH), wherein the plurality of TPC bits are not knownwhen they are received. The radio links that belong to the same radiolink set broadcast the same values of transmit power control (TPC) bits.The radio links that belong to different radio link sets may broadcastdifferent TPC bits. The user equipment 120 may receive TPC bits viamultiple radio links, for example, RL₁ and RL₂ simultaneously. In ahandover situation, the user equipment 120 may receive signals frommultiple radio link sets simultaneously.

The WCDMA specification defines the physical random access channel(PRACH) for mobile phone uplinks and the acquisition indicator channel(AICH) for BTS downlinks. Communication is established when the userequipment 120 completes its search for a base station, for example, BS122 and synchronizes its PRACH uplink signal with the BTS AICH downlinksignal. When operating properly, the base station recognizes a PRACHpreamble from the user equipment 120 and responds with an AICH toestablish a communication link. The user equipment 120 may use the PRACHto transmit its setting of its open loop power control to the basestation 122. Incorrect data in the PRACH preamble or problems with thesignal quality may cause missed connections, disrupt the capacity of thecell or prevent response from the base station 122.

FIG. 1B is a block diagram of an exemplary radio frame format of adownlink dedicated physical channel (DPCH), in accordance with anembodiment of the invention. Referring to FIG. 1B, there is shown aradio frame format 102, with a time period T_(f) equal to 10 ms, forexample. The radio frame 102 may comprise a plurality of slots, forexample, 15 slots. Each of the slots in the radio frame 102, forexample, slot # 104 may comprise a plurality of dedicated physical datachannels (DPDCH) and a plurality of dedicated physical control channels(DPCCH). The time period of each slot in the radio frame 102, forexample, time period of slot # i may be equal to 10*2^(k) bits, wherek=0 . . . 7, for example.

The DPDCH is a type of downlink channel, which may be represented as anI/Q code multiplexed within each radio frame 102. The downlink DPDCH maybe utilized to carry data, for example, data 1 154 comprising N_(data1)bits and data 2 160 comprising N_(data2) bits. There may be zero, one,or a plurality of downlink dedicated physical data channels on eachradio link.

The DPCCH is a type of downlink channel, which may be represented as anI/Q code multiplexed within each radio frame 102. The downlink DPCCH maybe utilized to carry control information generated at the physicallayer. The control information may comprise a transmit power control(TPC) block 156 comprising N_(TPC) bits per slot, a transport formatcombination indicator (TFCI) block 158 comprising N_(TFCI) bits per slotand a pilot block 162 comprising N_(pilot) bits per slot.

Unlike the pilot bits 162 which are known a priori, that is, they areknown when received by a receiver, the TPC bits 156 may be known orunknown when they are received. The term “a priori” means “formed orconceived beforehand.” The phrase “not known” means that when some orall of the TPC bits are received at the receiver, the receiver cannotdetermine their actual values, and may need to determine the quality ofthe channel in order to determine whether the TPC bits are valid or not.Accordingly, various embodiments of the invention utilize channelquality to determine whether the TPC bits are valid or invalid.Therefore, conventional methods of computing a signal-to-noise ratio(SNR) metric based on multiplying the received signal by an a knownsequence may not be used here.

In an embodiment of the invention, the quality of the downlink controlchannel transmitted with the downlink dedicated physical channel (DPCH)may be determined. Within one downlink DPCH, dedicated data may betransmitted in time-multiplex manner with control information. Thecontrol information may comprise pilot bits, transport formatcombination indicator (TFCI) bits and transmit power control (TPC) bits.

The user equipment 120 may be enabled to estimate the quality of thereceived TPC bits. The user equipment 120 may be, for example, ahandheld phone or a wireless card in a laptop computer, for example. Ifthe TPC bits are received under reliable channel conditions, they may bedemodulated correctly by the user equipment 120 which in turn may detectcorrectly the power control commands that are communicated by theserving radio link, and adjust its transmit power appropriately, therebyavoiding interference. On the other hand, if the TPC bits are receivedunder poor channel conditions, the TPC commands may be decodedincorrectly by the user equipment 120 which in turn may be transmittinginappropriate transmit power levels, creating undesirable interferenceand limiting the system capacity.

In another embodiment of the invention, in instances when multiple RLsets are active, such as RL1 and RL2, multiple TPC commands may bereceived at the user equipment 120. The TPC commands derived from RL1and RL2 may comprise TPC bits, such as TPC bits 156. In addition, thereceived TPC bits from the multiple RL sets may be combined to determinea final TPC command for the user equipment 120. The final TPC commandmay be used by the user equipment 120 to determine whether to increaseor decrease its transmit power. In one embodiment of the invention, thetransmit power may be increased or decreased by a determined step size.Since some TPC commands may be received by the user equipment 120 underbetter channel conditions than others, a different weight value may beassigned to each TPC command in a radio link set.

In this regard, a reliability factor may be determined for each of theone or more TPC commands received by the user equipment 120 based on asign metric measurement, for example. The reliability factor may be usedto compute a weighted sum of the multiple received TPC commands,resulting in the accumulated final TPC command. In addition, thereliability factor of each received TCP command may be compared to athreshold value. If the reliability factor for a particular received TCPcommand is higher than the threshold value, the reliability factor andthe TCP command may not be used in the calculation of the final TCPcommand. The sign of the final TPC command may be used to determinewhether to increase or decrease the transmit power of the user equipment120.

FIG. 1C is a graph 180 illustrating the effect of a sign metric as anindicator of the quality of reception of the downlink DPCH, inaccordance with an embodiment of the invention. Referring to FIG. 1C,there is shown a graph of a probability of error (P_(e)) waveform 182and a graph of a probability of error with different signs(P_(diff.sign)) waveform 184 plotted against the signal to nose ratio(SNR) per TPC bit.

The bit error rate (BER) of the received TPC bits may be related to theprobability of receiving the TPC bits with different signsP_(diff.sign). By design, the TPC bit field in a given slot may beeither composed of ones, or of minus ones, or all TPC bits may betransmitted with the same sign. If the received TPC field comprises bitsof different polarity, it may be inferred that the TPC bits are receivedwith some probability of error. In an additive white gaussian noise(AWGN) channel, the BER of the TPC bits may be expressed according tothe following equation:

$P_{e} = {\frac{1}{2}{{erfc}( \sqrt{\frac{E_{b}}{N_{0}}} )}}$where E_(b)/N₀ is the SNR per bit.

The TPC bit field may be composed of 2 bits for example. The probabilityof receiving TPC bit 1 and 2 with different polarity may be equal to theprobability of receiving the TPC field as [−1,1] or [1,−1]. Thisprobability may be expressed according to the following equation:P _(diff.sign)=2·P _(e)·(1−P _(e))The graph 180 illustrates that the two variables P_(e) 182 andP_(diff.sign) 184 have a correlated behaviour versus SNR, hence theknowledge of P_(diff.sign) offers reliable insight on the quality ofreception of the TPC bits.

FIG. 2 is a block diagram illustrating a mechanism for determiningreliability weights in a WCDMA network, in accordance with an embodimentof the invention. Referring to FIG. 2, there is shown a plurality of TPCextraction fingers, for example, TPC extraction finger i 202 and TPCextraction finger j 204, a plurality of summing blocks 206 and 207, aplurality of sign detector blocks 208, a comparator block 210, aplurality of function blocks 212, a sum negative occurrences block 214,a divider block 216, and an averaging block 218.

A TPC sign metric may be computed corresponding to the TPC bits arrivingfrom a given radio link (RL) set, indexed by k. A receiver techniquethat uses several baseband correlators to individually process severalsignal multipath components, for example, a rake receiver may beutilized. The correlator outputs also known as fingers may be combinedto achieve improved communications reliability and performance. In amultipath-fading environment, with a receiver structure, for example, aRAKE or cluster processor (CPP) assigns fingers to the multiple receivedpaths, for example, TPC extraction finger i 202 and TPC extractionfinger j 204. The received TPC bits may be summed over those fingersbelonging to the same radio link (RL) set by the summing block 206. Ateach slot, a set of num_tpc TPC bits may be obtained and denoted as{TPC_(b1)(k), TPC_(b2)(k), . . . , TPC_(bnum) _(—) _(tpc)(k)}where k is index of the RL set and num_tpc is the number of TPC bits perslot.

The corresponding TPC command may be generated by summing the TPC bitsby the summing block 207 according to the following equation:

${{TPC}_{cmd}(k)} = {\sum\limits_{i = 1}^{{num}\;\_\;{tpc}}{{TPC}_{bi}(k)}}$The sign of each TPC bit detected by the sign detector blocks 208 may bethen compared to the sign of the TPC command by the comparator block210.

${{{TPC\_ sign}{\_ diff}( {i,k} )} = ( {{{sign}( {{TPC}_{bi}(k)} )}\overset{?}{=}( {{TPC}_{cmd}(k)} )} )},{i = 1},\ldots\mspace{14mu},{num\_ tpc}$The value of TPC_sign_diff(i,k) may be equal to 0 if there is a signagreement; otherwise it may be equal to 1.

A variable denoted by, for example, CorrectBits may be computedutilizing the plurality of function blocks 212 according to thefollowing equation:CorrectBits(i,k)=1−2·TPC_sign_diff(i,k), i=1, . . . , num_tpcThe number of sign disagreements, or equivalently TPC failures, over thenum_tpc bits may be calculated by the sum negative occurrences block 214according to the following algorithm:

TPC _failures(k) = 0 for i = 1,···,num_tpc { if (CorrectBits(i,k) ≦ 0)TPC _failures(k) = TPC _failures(k)+1; }

The sign metric for RL set k updated every slot may be calculated by thedivider block 216 according to the following equation:

${{sign\_ metric}(k)} = \frac{{TPC\_ failures}(k)}{num\_ tpc}$The generated sign metric sign_metric (k) may be averaged over a giventime window by the averaging block 218 to generate sign_metric_avg(k)220. An integrate-and-dump method or an IIR filter may be utilized tocarry out the averaging operation, for example. The averaged signmetric, sign_metric_avg(k) 220 may be used as a reliability weight valuewk during the determination of a total TPC command for use by the userequipment 120 (FIG. 1A).

FIG. 3 is a block diagram illustrating another mechanism for determiningreliability weights in a WCDMA network, in accordance with an embodimentof the invention. Referring to FIG. 3, there is shown a plurality of TPCextraction fingers, for example, TPC extraction finger i 302 and TPCextraction finger j 304, a plurality of summing blocks 306, 308 and 310,a plurality of sign detector blocks 312 and 314, a comparator block 316,and an averaging block 318.

A TPC sign metric may be computed corresponding to the TPC bits arrivingfrom a given radio link (RL) set, indexed by k. In a multipath-fadingenvironment with a receiver structure, for example, a RAKE or clusterpath processor (CPP), the receiver structure may assign fingers to themultiple received paths, for example, TPC extraction finger i 302 andTPC extraction finger j 304. The received TPC bits may be summed overall fingers belonging to the same radio link (RL) set by the summingblock 306. At each slot, a set of num_tpc TPC bits may be obtained anddenoted as{TPC_(b1)(k), TPC_(b2)(k), . . . , TPC_(bnum) _(—) _(tpc)(k)}where k is index of the RL set and num_tpc is the number of TPC bits perslot.

In accordance with an embodiment of the invention, the sign of each bitmay be compared against each other. For slot formats where num_tpc>2,the algorithm may first combine the bits in a manner such that itreduces the number of bits to 2. The reduction to 2 bits may be achievedby the summing blocks 308 and 310 according to the following equations:

${{{TPC}_{1}(k)} = {\sum\limits_{{i = 1},3,\;\ldots}^{{num}\;\_\;{tpc}}{{TPC}_{bi}(k)}}},$which may represent summation over odd-indexed bits, and

${{{TPC}_{2}(k)} = {\sum\limits_{{i = 2},4,\;\ldots}^{{num}\;\_\;{tpc}}{{TPC}_{bi}(k)}}},$which may represent summation over even-indexed bits. The sign of TPCbit 1 and TPC bit 2 may be detected by the sign detector blocks 312 and314 and compared against each other by the comparator block 316,yielding the sign metric according to the following equation:

${{sign\_ metric}(k)} = ( {{{sign}( {{TPC}_{1}(k)} )}\overset{?}{=}{{sign}( {{TPC}_{2}(k)} )}} )$The value of sign_metric(k) may be equal to 0 if is there is a signagreement, otherwise it may be equal to 1. The generated sign metricsign_metric(k) may be averaged over a given time window by the averagingblock 318 to generate sign_metric_avg(k) 320.

The averaging block 318 may be implemented via an infinite impulseresponse (IIR) filter, or via a moving average window of fixed size. Thelength of the averaging filter may be selected with respect to thechannel variation rate that may be measured by Doppler frequency. TheDoppler frequency may be an inverse function of the channel coherencetime. The channel coherence time may correspond to a time period withinwhich two observations of the channel are highly correlated, forexample. In addition, the averaging block 318 may be selected so thatthe channel quality may be estimated fast enough so that it tracks thechannel fades over time. In such instances, the length of the filter ofthe averaging block 318 may be smaller than the channel coherence time.The averaging block 318 may also be selected so that the estimatedchannel quality is a long-term measurement, averaged over a plurality offades. In such instances, the length of the filter may be longer thanthe channel coherence time.

FIG. 4 is a block diagram of an exemplary system for weightedcombination of multiple TPC commands, in accordance with an embodimentof the invention. Referring to FIG. 4, the system 400 may comprise aplurality of received TPC commands 402 a, . . . , 402 n, a plurality ofsign extraction blocks 404 a, . . . , 404 n, a plurality of multipliers406 a, . . . , 406 n, a plurality of zero multiplication blocks 405 a, .. . , 405 n, a plurality of adders 410 and 416, and a transmit poweradjustment block 414. The received TPC commands 402 a, . . . , 402 n maycorrespond to radio link sets 1, . . . , k, respectively. In thisregard, a total of k received TPC commands may be used in thedetermination of a final or adjusted TPC command 412.

The sign extraction blocks 404 a, . . . , 404 n may comprise suitablecircuitry, logic, and/or code and may enable determination of the signof a corresponding TPC command. In this regard, the sign extractionblocks 404 a, . . . , 404 n may generate either (−1) or (+1) as a finalresult. The generated signs may be communicated to the correspondingmultipliers 406 a, . . . , 406 n. The multipliers 406 a, . . . , 406 nmay comprise suitable circuitry, logic, and/or code and may enablemultiplication of the received sign by a value equal to the subtractionof a corresponding reliability weight value 408 a, . . . , 408 n from athreshold value, or reliability_threshold to generate weighted signvalues.

In one embodiment of the invention, it may be determined whether each ofthe reliability weight values 408 a, . . . , 408 n is higher than thereliability_threshold. If a reliability weight value is higher than thereliability_threshold, the weighted sign value may be multiplied by zeroby a corresponding zero multiplication block from the plurality of zeromultiplication blocks 405 a, . . . , 405 n. In this regard, if thereliability weight value is higher than the reliability_threshold, thecorresponding weighted sign value may not be included in thedetermination of the final TPC command 412.

If the reliability weight value is smaller than thereliability_threshold, the weighted sign values may be added by theadder 410 to generate the total TPC command 412. The transmit poweradjustment block 414 may comprise suitable circuitry, logic, and/or codeand may enable adjustment of the transmit power based on the determinedfinal TPC command 412. The final TPC command 412 may be used to adjustthe transmit power based on, for example, the sign of the final TPCcommand 412.

In one embodiment of the invention, the received TPC commands 402 a, . .. , 402 n may belong to the same radio link (RL) set. Since radio linksbelonging to the same RL set transmit the same TPC command, the TPCcommands originating from radio links belonging to the same RL set maybe combined with equal weights. In this regard, the reliability weights408 a, . . . , 408 n may be the same, for example 1 or −1.

In another embodiment of the invention, the received TPC commands 402 a,. . . , 402 n may belong to different RL sets. For example, the receivedTPC commands 402 a, . . . , 402 n may belong to RL sets 1, . . . , K,respectively. In this regard, there may be one TPC command for each ofthe K RL sets, TPC_cmd(k), k=1, . . . K. The overall accumulated commandTPC_cmd 512 may be computed using the following exemplary pseudo code:

Initialize the accumulated command to zero, Accum_cmd = 0 For (k=loopover RL sets) { Take sign of TPC_cmd(k) If (wk< reliability_threshold)Accum_cmd = Accum_cmd + (sign of TPC_cmd(k) ) * ( reliability_threshold− wk) }where wk are the reliability weights 408 a, . . . , 408 n.

The value of Accum_cmd may correspond to the total TPC command 412. Thetransmit power adjustment block 414 may determine whether to increase ordecrease the transmit power based on the sign of Accum_cmd. For example,if the sign of Accum_cmd is negative, the transmit power may bedecreased by a given step size. Similarly, if the sign of Accum_cmd ispositive, the transmit power may be increased by a given step size.

The reliability_threshold may be selected to correspond to a TPC commanderror rate of X %, for example. In this regard, a TPC command with anestimated reliability weight value corresponding to an error rate of X %or higher may be discarded from the calculation of the final TPC command412. With regard to an embodiment of the invention described in FIG. 2,the reliability_threshold value may be a function of the number of TPCbits per slot, denoted by, for example, num_tpc. In this regard, theremay be a different value of reliability_threshold for each possiblenum_tpc value. In addition, different slot formats may have differentnum_tpc values. With regard to an embodiment of the invention describedin FIG. 3, only one value for reliability_threshold may be usedresulting from the reduction of the TPC bits to 2 bits. Thereliability_threshold value may be valid for all possible num_tpcvalues.

The reliability weight values 408 a, . . . , 408 n may be calculatedbased on computing a TPC sign metric, sign_metric_avg(k), correspondingto the TPC bits arriving from a given RL set. In this regard, thereliability weight value wk may be calculated from the followingequation:w _(k)=sign_metric_avg(k)

Calculation of an exemplary TPC sign metric, sign_metric_avg(k),corresponding to the TPC bits arriving from a given RL set, is describedabove with regard to FIGS. 2 and 3.

FIG. 5 is a flowchart illustrating exemplary steps for determining atotal TPC command in a WCDMA network, in accordance with an embodimentof the invention. Referring to FIGS. 4 and 5, at 502, reliabilityweights 408 a, . . . , 408 n may be determined for each one of aplurality of received TPC commands 402 a, . . . , 402 n for K radio link(RL) sets. The reliability weights 408 a, . . . , 408 n may bedetermined based on a sign metric. At 504, the sign extraction blocks404 a, . . . , 404 n may determine the sign of each of the received TPCcommands 402 a, . . . , 402 n. At 506, a counter i may be incrementedby 1. At 508, it may be determined whether reliability weight w_(i) isgreater than a reliability threshold value. If the reliability weightw_(i) is greater than the reliability threshold value, at 510, w_(i) maybe discarded from the calculation of the total TPC command 412.Processing may then resume at step 516.

If the reliability weight w_(i) is not greater than the reliabilitythreshold value, at 512, the determined sign of the received TPC commandfor RL set i may be multiplied by a value equal to the subtraction ofthe corresponding reliability weight w_(i) from thereliability_threshold value to generate a weighted TPC commandw_TPC_(i). At 514, the total TPC command 412 may be incremented by theweighted TPC command w_TPC_(i). At 516, it may be determined whetheri=k. If i is lower than k, processing may resume at step 508. If i isequal to k, at 518, the transmit power adjustment block 414 may adjustthe transmit power based on the total TPC command 412.

In accordance with an embodiment of the invention, a method and systemfor processing TPC commands in a WCDMA network based on a sign metricmay comprise circuitry that enables calculation of a sign metric of adownlink DPCH 102 based on a plurality of TPC bits 156 received via thedownlink DPCH 102. A value of at least one of the plurality of TPC bits156 may not be known when the at least one of the plurality of TPC bits156 is received. The sign metric may specify an error associated withthe plurality of TPC bits. Transmit power adjustment block 414 withinthe user equipment 120 may enable adjusting of transmit power for asignal transmitted via at least one uplink communication channel basedon the calculated sign metric. At least one processor within the userequipment 120, such as CPU 142 may enable calculation of at least onereliability weight value for at least a portion of the received TCP bits156, based on the calculated sign metric.

The at least one processor 142 within the user equipment 120 may enablecalculation of a total TPC command 412 for the at least one uplinkcommunication path based on the plurality of received TPC bits 156 andthe calculated at least one reliability weight value 408 a, . . . , 408n. The at least one processor 142 within the user equipment 120 mayenable discarding of a selected one of the at least one reliabilityweight value from the calculation of the total TPC command, if theselected one of the at least one reliability weight value is higher thana threshold value. The transmit power adjustment block 414 within theuser equipment 120 may enable adjusting of the transmit power for the atleast one uplink communication channel based on the calculated total TPCcommand. Summing circuitry within the user equipment 120, such assumming blocks 206 and/or 207 may enable summing of portions of theplurality of TPC bits 156 that are received via a plurality ofmultipaths over the downlink dedicated physical channel to generate aTPC command. The comparator 210 within the user equipment 120 may enablecomparing of a sign of each of the plurality of TPC bits 156 with a signof the generated TPC command.

The processor 142 within the user equipment 120 may enable calculationof a sign indicator based on the comparison of the sign of each of theplurality of TPC bits with the sign of the generated TPC command. Theprocessor 142 within the user equipment 120 may enable calculation of anumber of TPC failures between the sign of each of the plurality of TPCbits with the sign of the generated TPC command based on the calculatedsign indicator. The processor 142 within the user equipment 120 mayenable calculation of the sign metric of the DPCH 102 based on thecalculated number of TPC failures between the sign of each of theplurality of TPC bits with the sign of the generated TPC command.Summing blocks 306, 308 and/or 310 within the user equipment 120 mayenable summing of portions of the plurality of TPC bits 156 over oddindexed bits to generate a first TPC bit.

Summing blocks 306, 308 and/or 310 within the user equipment 120 mayenable summing of portions of the plurality of TPC bits 156 over evenindexed bits to generate a second TPC bit. The comparator 316 within theuser equipment 120 may enable comparing of a sign of the generated firstTPC bit and a sign of the generated second TPC bit. The processor 142within the user equipment 120 may enable calculation of the sign metricof the DPCH 102 based on the comparison of the sign of the generatedfirst TPC bit and the sign of the generated second TPC bit.

Another embodiment of the invention may provide a machine-readablestorage having stored thereon, a computer program having at least onecode section for signal processing, the at least one code section beingexecutable by a machine for causing the machine to perform steps asdisclosed herein. For example, computer program and/or equivalent codethereof, may be stored in memory 144 and may be executed by processor142.

Accordingly, aspects of the invention may be realized in hardware,software, firmware or a combination thereof. The invention may berealized in a centralized fashion in at least one computer system or ina distributed fashion where different elements are spread across severalinterconnected computer systems. Any kind of computer system or otherapparatus adapted for carrying out the methods described herein issuited. A typical combination of hardware, software and firmware may bea general-purpose computer system with a computer program that, whenbeing loaded and executed, controls the computer system such that itcarries out the methods described herein.

One embodiment of the present invention may be implemented as a boardlevel product, as a single chip, application specific integrated circuit(ASIC), or with varying levels integrated on a single chip with otherportions of the system as separate components. The degree of integrationof the system will primarily be determined by speed and costconsiderations. Because of the sophisticated nature of modernprocessors, it is possible to utilize a commercially availableprocessor, which may be implemented external to an ASIC implementationof the present system. Alternatively, if the processor is available asan ASIC core or logic block, then the commercially available processormay be implemented as part of an ASIC device with various functionsimplemented as firmware.

The invention may also be embedded in a computer program product, whichcomprises all the features enabling the implementation of the methodsdescribed herein, and which when loaded in a computer system is able tocarry out these methods. Computer program in the present context maymean, for example, any expression, in any language, code or notation, ofa set of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform. However, other meanings of computer program within theunderstanding of those skilled in the art are also contemplated by thepresent invention.

While the invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiments disclosed, but that the present inventionwill include all embodiments falling within the scope of the appendedclaims.

1. A method for signal processing, the method comprising: generating asign metric of a downlink dedicated physical channel (DPCH) based on aplurality of transmit power control (TPC) bits received via saiddownlink DPCH, wherein a value of at least one of said plurality of TPCbits is not known when said at least one of said plurality of TPC bitsis received, and said sign metric specifies an error associated withsaid plurality of TPC bits; and adjusting transmit power for a signaltransmitted via at least one uplink communication channel based on saidgenerated sign metric.
 2. The method according to claim 1, comprisingaveraging said sign metric over a time window.
 3. The method accordingto claim 2, comprising summing portions of said plurality of TPC bitsover even indexed bits to generate a second TPC bit.
 4. The methodaccording to claim 3, comprising comparing a sign of said generatedfirst TPC bit and a sign of said generated second TPC bit.
 5. The methodaccording to claim 4, comprising generating said sign metric of saidDPCH based on said comparing of said sign of said generated first TPCbit and said sign of said generated second TPC bit.
 6. The methodaccording to claim 1, comprising generating a total TPC command for saidat least one uplink communication path based on said plurality ofreceived TPC bits and at least one reliability weight value associatedwith said generated sign metric.
 7. The method according to claim 6,comprising, if a selected one of said at least one reliability weightvalue is higher than a threshold value, discarding said selected one ofsaid at least one reliability weight value from said generating of saidtotal TPC command.
 8. The method according to claim 7, wherein saidthreshold value is based on one or both of a TPC command error rateand/or a number of said plurality of received TPC bits per slot.
 9. Themethod according to claim 6, comprising adjusting said transmit powerfor said at least one uplink communication channel based on saidgenerated total TPC command.
 10. The method according to claim 1,comprising: summing portions of said plurality of TPC bits that arereceived via a plurality of multipaths over said downlink dedicatedphysical channel to generate a TPC command; and comparing a sign of eachof said plurality of TPC bits with a sign of said generated TPC command.11. The method according to claim 10, comprising calculating a signindicator based on said comparing of said sign of each of said pluralityof TPC bits with said sign of said generated TPC command.
 12. The methodaccording to claim 11, comprising calculating a number of TPC failuresbetween said sign of each of said plurality of TPC bits with said signof said generated TPC command based on said calculated sign indicator.13. The method according to claim 12, comprising calculating said signmetric of said DPCH based on said calculated number of TPC failuresbetween said sign of each of said plurality of TPC bits with said signof said generated TPC command.
 14. The method according to claim 1,comprising summing portions of said plurality of TPC bits over oddindexed bits to generate a first TPC bit.
 15. A system for signalprocessing, the system comprising: circuitry that enables generating asign metric of a downlink dedicated physical channel (DPCH) based on aplurality of transmit power control (TPC) bits received via saiddownlink DPCH, wherein a value of at least one of said plurality of TPCbits is not known when said at least one of said plurality of TPC bitsis received, and said sign metric specifies an error associated withsaid plurality of TPC bits; and said circuitry enables adjusting oftransmit power for a signal transmitted via at least one uplinkcommunication channel based on said generated sign metric.
 16. Thesystem according to claim 15, wherein said circuitry enables averagingof said sign metric over a time window.
 17. The system according toclaim 15, wherein said circuitry enables generating a total TPC commandfor said at least one uplink communication path based on said pluralityof received TPC bits and at least one reliability weight valueassociated with said generated sign metric.
 18. The system according toclaim 17, wherein said circuitry enables adjusting of said transmitpower for said at least one uplink communication channel based on saidgenerated total TPC command.
 19. The system according to claim 17,wherein said circuitry enables discarding of said selected one of saidat least one reliability weight value from said generating of said totalTPC command, if a selected one of said at least one reliability weightvalue is higher than a threshold value.
 20. The system according toclaim 19, wherein said threshold value is based on one or both of a TPCcommand error rate and a number of said plurality of received TPC bitsper slot.
 21. The system according to claim 15, wherein said circuitryenables summing of portions of said plurality of TPC bits that arereceived via a plurality of multipaths over said downlink dedicatedphysical channel to generate a TPC command, and wherein said circuitryenables comparing of a sign of each of said plurality of TPC bits with asign of said generated TPC command.
 22. The system according to claim21, wherein said circuitry enables calculation of a sign indicator basedon said comparison of said sign of each of said plurality of TPC bitswith said sign of said generated TPC command.
 23. The system accordingto claim 22, wherein said circuitry enables calculation of a number ofTPC failures between said sign of each of said plurality of TPC bitswith said sign of said generated TPC command based on said calculatedsign indicator.
 24. The system according to claim 23, wherein saidcircuitry enables calculation of said sign metric of said DPCH based onsaid calculated number of TPC failures between said sign of each of saidplurality of TPC bits with said sign of said generated TPC command. 25.The system according to claim 15, wherein said circuitry enables summingof portions of said plurality of TPC bits over odd indexed bits togenerate a first TPC bit.
 26. The system according to claim 25, whereinsaid circuitry enables summing of portions of said plurality of TPC bitsover even indexed bits to generate a second TPC bit.
 27. The systemaccording to claim 26, wherein said circuitry enables comparing of asign of said generated first TPC bit and a sign of said generated secondTPC bit.
 28. The system according to claim 27, wherein said circuitryenables generation of said sign metric of said DPCH based on saidcomparison of said sign of said generated first TPC bit and said sign ofsaid generated second TPC bit.